Paul Revere's Ride (54 page)

In the evening and night of April 18 (when the British expedition set off for Concord, and Paul Revere made his midnight ride) clearing followed rapidly. Revere remembered in his letter to Jeremy Belknap that the night was “very pleasant.” Sanderson described it as “a pleasant evening” (Phinney,
Lexington
23).

For the 19th of April, the primary evidence of twelve diaries is highly consistent. In Cambridge, Harvard professor John Winthrop took two readings of his thermometer that day. At six o’clock in the morning, he noted that the temperature was 46 degrees, the barometer 29.56 inches and rising, the sky fair, and light winds from the west. At one o’clock in the afternoon, the temperature had risen to 52 degrees, the sky was fair with clouds, and the west wind had freshened. At that point he noted, “battle of Concord will put a stop to observing.” He and his wife Hannah fled for their lives.

Other diarists described the weather that day in the same way. Lexington’s minister Jonas Clarke found a moment to note that the day was “clear.” In Boston, Dr. John Jeffries wrote, “clear and fair, fresh wind at W.” The Rev. William Marrett in Burlington thought the day was “fair, windy and cold.” Paul Litchfield of Scituate described it as “somewhat blustery and cool.” Elizabeth Stiles in Newport, R. L., recorded a temperature of 53 degrees at 11 am, fair skies and the wind from west. Jeremy Belknap, in Dover, N. H., called it “fair, windy, cool, w[est wind].” Ebenezer Gay, in Suffield, Conn., thought the day was “fair, cold.” Dr. Nathaniel Ames, in Dedham described it as “clear.” William Clark in the same town described the day as “fair” with a “strong chilly west wind.” An anonymous weather diary, now in the Concord Free Public Library, described the 19th as “fair with a westerly wind.”

The best secondary account is David Ludlum, “The Weather of Independence,” in
The Country Journal New England Weather Book
(Boston, 1976), 126-28. Ludlum, editor of the American Meteorological Society’s journal
Weatherwise,
concludes that “these records indicate that a cold front passed through eastern Massachusetts about noon on April 18, bringing an end to the showery conditions, a shift of wind to the west, a rising barometer, and a rather rapid postfrontal clearing. Visibility was good late in the evening when the signal lamps were hung.” This is by far the most accurate judgment, but requires amendment in one detail. Some diaries reported showers persisting into the late afternoon of the 18th. After two days of rain, the ground, normally wet in mid-April, was very soft—as one of Paul Revere’s pursuers discovered by experience. The streams were high, as Smith’s British infantry learned the hard way. By all accounts, the day of the battle was crisp, cool, and fair, with a rising westerly wind and fluffy cumulus clouds scudding across bright blue skies.

Late in the day, another storm system moved rapidly through the area, with a red sunset, and later a cold rain that made a miserable night for both the American militia who were “lying on their arms” at Cambridge, and the British Regulars who were sleeping in the open on Bunker Hill.

SOURCES: The Nathaniel Ames Diary and William Clark Diary, Dedham Historical Society; an anonymous weather diary, CFPL; the Winthrop weather diary, Harvard Archives; Jonas Clarke Diary, MHS; diaries of Jeremy Belknap, Ebenezer Gay, Joseph Andrews, and Paul Litchfield, all in MHS. The Marrett Diary is quoted in Frothingham,
Siege of Boston,
59, 84n; the Stiles Diary and Jeffries Diary, in Ludlum,
The Country Journal New England Weather Book, 127
.

APPENDIX I

The Moon, April 18-19, 1775

Many participants remembered that the moon was nearly full on the night of April 18-19, 1775. “The moon shone bright,” Paul Revere wrote in his deposition. His fellow captive Sanderson wrote independently, “It was a bright moon-light after the rising of the moon, and a pleasant evening” (Phinney,
Lexington,
31).

These memories have been confirmed by two American astronomers, Donald W. Olson and Russell L. Doescher, who studied this subject in detail, and found that the nearest full moon occurred on April 15, 1775, and the last quarter on April 22. On the night of the midnight ride, they calculate that “there was indeed a bright waning-gibbous moon, 87 percent sunlit, in Boston on the night of April 18, 1775.” They estimate that the moon rose over Boston at approximately 9:53 p.m., local apparent solar time (approximately 25 minutes later than our modern Eastern Standard Time).

On that night Olson and Doescher reckon that the moon had a strong southern declination of -18 degrees. If Revere’s friends were rowing him across the Charles River at approximately 45 minutes after moonrise, the moon would have been very low in the southern sky—6 degrees above the horizon, on a true bearing of 121 degrees.

Revere’s course from the North End of Boston to Charlestown’s ferry landing was approximately 330 degrees. The moon was almost directly behind him, and as it was only 6 degrees above the horizon, his boat would have been shrouded in the dark moonshadow of the town’s skyline, and very difficult to see from the deck of HMS
Somerset,
or even from British guardboats that were patrolling the river that night.

The transit of the moon occurred at 2:42 a.m. according to the computations of two other astronomers, Jacques Vialle and Darrel Hoff. The marker in the Minute Man National Historical Park that refers to a third quarter moon is not correct.

See Donald W. Olson and Russell L. Doescher, “Astronomical Computing: Paul Revere’s Midnight Ride,”
Sky and Telescope,
April 1992, pp. 437-40; also Jacques Vialle and Darrel Hoff, “The Astronomy of Paul Revere’s Ride,”
Astronomy
20 (1992): 13-18.

APPENDIX J

Tidal Movements, the British March, and the Midnight Ride, April 18-19, 1775

Shakespeare observes that “there is a tide in the affairs of men; which, taken at the flood, leads on to fortune”
(Julius Caesar, IV, iii, 217)
. So it was for Paul Revere, but General Gage would have been luckier at the ebb.

Tidal movements in the Charles River and Boston’s Back Bay had an important impact on these events. Paul Revere remembered that when he crossed the Charles River at approximately 10:30 to 11:00 p.m., “It was then young flood.” The strong Boston tide was flowing into the harbor and running westward up the estuary of the Charles River.

At that same hour, the British troops were moving across the Charles River to Lechmere Point in Cambridge. Lt. William Sutherland wrote that when they marched along the river at 2 a.m., “the tide being in we were up to our middles.” Mackenzie remembered that the men were “obliged to wade, halfway up to their thighs, through two inlets, the tide being by that time up.”

Modern computations confirm the accuracy of these accounts. Professors Olson and Doescher, using a method of harmonic analysis, estimate that on the afternoon of April 18, 1775, high tide in Boston harbor occurred at 1:14 p.m. local apparent solar time. Low water followed that evening at 7:19 p.m. and high tide again at 1:26 a.m. in the morning. These results confirm that the tide was rising when Revere and the British soldiers were crossing the river.

Early American almanacs were even closer to the descriptions of the participants. Three colonial almanacs variously estimated the time of high tide on the morning of April 19 at approximately 2:34 (Low) 2:36 (Isaiah Thomas), and 2:39 (Bickerstaff).

All this was an advantage for Paul Revere, and a problem for the British expedition. At the point where Revere crossed, the river flowed west around a bend. His course to Charlestown took him upstream. The Regulars crossed further west where the river was flowing southwest. Their course to Cambridge was downstream. Revere’s passage was comparatively short, and as his route took him diagonally upstream he was moving with the tide. The British troops were moving diagonally downstream against the tide over a longer distance. Revere was traveling in a small rowboat with two experienced Boston watermen. The British troops were in heavy, overloaded longboats. The tide gave Revere an important advantage, and was a factor in speeding him on his way, while retarding the progress of the British troops.

See Donald W. Olson and Russell L. Doescher, “Astronomical Computing: Paul Revere’s Midnight Ride,”
Sky and Telescope,
April 1992, pp. 437-40.

APPENDIX K

The British Concord Expedition: The Problem of Numbers

No official count of troop strength has been found for this mission. Estimates by participants and eyewitnesses ranged between 600 and 900 men. Barker thought it numbered “about 600 men”; an officer of the 59th Foot, “600 men including officers”; Evelyn, “near 700”; an anonymous light infantryman, precisely 756; and Richard Pope, “nearly 800 men.” One observer, Boston printer John Boyle, counted “about 900 Regular troops, but his estimate has been rejected by all historians of the battle as too high. Cf. John Boyle, “Boyles Journal of Occurrences in Boston, 1759-1778,”
NEHGR
85 (1931) 8.

The estimates of historians have tended to vary according to their politics. In general, the more Whiggish the scholar, the larger his estimate of British numbers; the more Tory or Anglophile, the smaller the force becomes. The Whig historian Gordon reckoned the force at “800 men or better.” Bancroft, Coburn, Frothingham, Hale, Hudson, Lossing, and Shattuck were content with 800. Robert Gross preferred “seven to eight hundred.” French, Tourtellot, and Galvin reckoned “in the neighborhood of 700.” The American Anglophile Harold Murdock extrapolated from average company strength of the 23rd Foot (28.2 men) to a controlled guess of 588 rank and file.

These estimates derive mainly from impressions of contemporaries, and the conventional judgments of other scholars, and in the case of Murdock from a strength report for a single regiment, drawn from the diary of Frederick Mackenzie.

Monthly strength reports for all units engaged at Lexington and Concord are missing in the Public Record Office, but another source helps to settle the question. Regimental rosters and paylists are available for the 1774-75. Each regiment submitted twice a year a roster, sworn before a magistrate and witnesses. These documents were meticulously compiled
in elaborate detail. A separate folio sheet was prepared for each company, listing by name and rank every man who had served in the unit since the last report, with dates of duty, promotions, transfers, leaves, desertions, discharges, detached duty, etc. The Boston regiments in general submitted reports in the winter of 1774—75, and again in the summer of 1775. These documents were not snapshots, but moving pictures. They are imperfect in some details. Men who were relieved from duty for sickness or wounds or special assignments were listed only for the end of the reporting period, but not for other dates. Other movements are noted throughout the reporting period. These records reported an extraordinarily high rate of turnover. Men were frequently transferred in and out of individual companies, commonly from other units in the same regiment. Recruits and replacements arrived throughout the period.

No rosters were found for the British Marines before 1777. By the beginning of that year, the “American battalion” that had served at Boston had moved to Halifax. Its grenadier company had a strength of 3 officers and 29 men. Its light infantry company (the same that marched to Concord) was very much larger, with 117 other ranks; but it is not clear that the company was of similar size in April, 1775. Another method of estimation was used here to avoid an overcount. The total strength of the British Marine battalion in Boston was reported by its commander Major Percy at 387 effectives, 22 percent larger than the mean effective strength of the army regiments in Boston on April 1, 1775. An estimate for the Marine grenadiers and light infantry companies was added here in the same ratio, as 122% of mean strength in other companies. If the earliest pay rosters are an accurate indicator, the true strength was not 43 but 73 rank and file. The smaller number is used here, as a lower-bound estimate. Contingency men are not included.